Cloning of three ZIP/NRAMP transporter genes from a Ni hyperaccumulator plant Thlaspi japonicum and their Ni2+-transport abilities
Cloning of three ZIP/NRAMP transporter genes from a Ni hyperaccumulator plant Thlaspi japonicum and their Ni2+-transport abilities
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DOI：
10.1016/j.plaphy.2005.07.006
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发表时间：
2005-08-01
影响因子：
6.5
通讯作者：
Obata, H
中科院分区：
文献类型：
--
作者：
Mizuno, T;Usui, K;Obata, H
镍的动态平衡对植物细胞的活动是至关重要的，但镍的运输和输送机制尚不清楚。为了阐明ZIP和NRAMP金属转运蛋白在镍离子转运和动态平衡中的作用，我们克隆了它们的同源基因，并通过在酵母中的表达来研究它们对镍的转运能力。所克隆的两个Zip转运蛋白基因(TjZnt1、TjZnt2)和一个Nramp转运蛋白基因的氨基酸序列分别与拟南芥的TcZNT1和TcZNT2以及拟南芥的AtNRAMP4高度同源，预测为具有6或12个跨膜区的完整膜蛋白。TjZNT1和TjZNT2在跨膜区III和IV之间的细胞质区域有两个长的富含组氨酸的结构域。TjNRAMP4在跨膜区VIII和IX之间保守一个共同的转运蛋白基序。转化TjZNT1和TjZNT2的酵母对Ni2+的耐受性随着基因表达的增加而显著提高。相反，TjNramp4的表达导致细胞对Ni2+的敏感性和Ni2+浓度升高。这些数据表明，ZIP/NRAMP转运蛋白参与了镍超积累植物的Ni2+动态平衡。TjZNT1具有转运锌、镉和锰的能力，TjZNT2也具有转运锌和锰的能力，但TjNRAMP4只能转运Ni2+，而不能转运锌、镉和锰。(C)2005年爱思唯尔集团。版权所有。
Ni homeostasis is essential for plant cell activity, but the mechanisms of Ni-transport and delivery are unknown. To elucidate the role of ZIP and NRAMP metal-transporters for Ni2+-transport and homeostasis, we cloned their homologous genes from the Ni hyperaccumulator Thlaspi japonicum, and investigated their Ni-transporting abilities by expression in yeast. The deduced amino acid sequences of the two Zip transporter genes (TjZnt1, TjZnt2) and one Nramp transporter gene cloned had high homologies with TcZNT1 and TcZNT2 of Thlaspi caerulescens and AtNRAMP4 of Arabidopsis thaliana, respectively, and were predicted as integral membrane proteins with 6 or 12 transmembrane domains. TjZNT1 and TjZNT2 had two long histidine-rich domains in the putative cytoplasmic domain between transmembrane domains III and IV. TjNRAMP4 conserved a consensus transporter motif between transmembrane domains VIII and IX. The yeast transformed with TjZNT1 or TjZNT2 showed a marked increase in Ni2+ tolerance with the gene expression. In contrast, the expression of TjNramp4 caused elevation of Ni2+ sensitivity and Ni2+ concentration. These data suggest that ZIP/NRAMP transporters participate in Ni2+ homeostasis of Ni hyperaccumulator plants. TjZNT1 had Zn2+-, Cd2+- and Mn2+-transporting abilities and TjZNT2 also had Zn2+- and Mn2+-transporting abilities, but TjNRAMP4 could transport Ni2+ but not Zn2+, Cd2+ or Mn2+. (c) 2005 Elsevier SAS. All rights reserved.